Abstract
Background/purpose
Atypical clubfeet are distinct from idiopathic clubfeet. It is resistant to correction by conventional casting methods and often requires a modification of Ponseti's casting technique. Although the initial correction rates are reasonable, relapse and complications are frequent. There is limited literature on the results of modified Ponseti casting of these feet. We conducted this meta-analysis to study a few important aspects of atypical/complex clubfeet treatment by the modified Ponseti technique.
Research question
What are the results of atypical or complex clubfeet after treatment by the modified Ponseti technique?
Methodology
Five electronic databases (PubMed, Embase, Scopus, Ovid, and Cochrane Library) were searched for articles reporting on the results of atypical/complex clubfeet treated by the modified Ponseti technique. Details of the number of casts required for correction, rate of percutaneous Achilles tenotomy (PAT), other soft tissue procedures required, complications, and relapse rates were extracted into spreadsheets, and meta-analysis was carried out using OpenMeta Analyst software.
Results
Ten studies were included for analysis with a total of 240 patients with 354 clubfeet. The initial correction was achieved in all feet. A pooled analysis of the data showed that a mean of six casts was required for the initial correction. The rate of PAT was 98.3%. The overall complication rate was 16.8%. 7.2% required an additional soft tissue procedure apart from the PAT, and relapse of the deformity was observed in a mean of 19.8% cases.
Conclusion
Modified Ponseti technique is effective in the initial management of atypical/complex clubfeet. Although the PAT rate is slightly higher in the Modified Ponseti technique, the remaining result parameters are comparable with the results of idiopathic clubfoot managed with the Ponseti method of casting. However, these children should be kept under follow-up for a longer duration to find the exact relapse rates.
Keywords: Atypical, Complex, Clubfoot, CTEV, Modified ponseti, Relapse
1. Introduction
Congenital talipes equinovarus (CTEV) or clubfoot is the most common congenital malformation of the foot, with a reported incidence of 1.1–1.6 per 1000 live births.1 Currently, non-operative management is the widely accepted mode of treatment for idiopathic CTEV, with the Ponseti method of casting being the most popular.2, 3, 4
Ponseti identified a group of patients with feet that remain resistant to the standard casting protocol. These feet have been called atypical or complex clubfeet and clinically present with a rigid equinus, short first metatarsal, short, stubby, hyperextended great toe, severe plantar flexion of all metatarsals, and a deep, transverse crease on the sole.5,6 The Achilles tendon is taut and fibrotic up to the mid-calf in these children. Such feet may be atypical from the beginning of treatment or may have become complex due to incorrect techniques of manipulation and casting.7 The terms “atypical” and “complex” clubfeet are often used interchangeably in the literature. Some authors consider atypical clubfoot as the idiopathic untreated entity and the complex clubfoot as the one formed due to improper casting and slippage.8 We have considered both the conditions to be the same for the sake of evaluation, as they both require a modified Ponseti technique for successful correction. In the modified technique, plantar flexed metatarsals are corrected by holding the ankle with both hands, keeping the thumbs under the metatarsals, and applying dorsiflexion force. The feet are not abducted beyond 40°, as continued attempts at abduction pushes the metatarsals into flexion and abduction but does not correct the hindfoot varus.5 The cast is applied in 110° of knee flexion instead of 90° to avoid slippage of the cast from the foot. Often, the PAT needs to be done even before an adequate abduction is achieved. After achieving an initial correction, a foot abduction brace is used with the involved foot in 40° of abduction, as opposed to the 70° abduction used for the idiopathic clubfeet.5 This modified casting protocol has a high rate of good initial correction but has been reported to be associated with frequent relapses and complications.7,8
Turco was the first to observe that the complex clubfeet were resistant to routine manipulation and casting. He also advised against operating on these cases, noting that early surgery leads to a “grotesquely deformed” foot.6 Ponseti in 2006 reported good clinical outcomes in 50 patients treated with his modified technique.5 Since then, several studies have been published using modified Ponseti casting protocol with varied results.5,7, 8, 9, 10, 11, 12, 13 However, the current literature on the overall results of treating these complex clubfeet is limited. This meta-analysis was conducted to determine the 1) Primary results in terms of the mean number of casts required for correction and need for percutaneous Achilles tenotomy (PAT) and 2) Secondary results in terms of a) other additional soft tissue procedures required, b) the complication rates during the treatment, and c) the relapse rates.
2. Materials and methods
2.1. Protocol and registration
The protocol for this systematic review and meta-analysis was submitted in PROSPERO on May 14, 2021 and registered on June 14, 2021 [CRD42021254968].
2.2. Search methodology
This study was conducted in accordance with the preferred reporting items for systematic review and meta-analysis (PRISMA) guidelines. A literature search was carried out in the electronic databases of PubMed, Embase, Scopus, Ovid, and Cochrane Library on May 06, 2021 using the keywords “[(atypical OR complex) AND (clubfoot OR clubfeet OR CTEV)]”. We included articles that were published from the inception of each database until the date of search. Duplicate articles and studies in languages other than English were excluded. After the eligible papers were finalized, a manual search of the bibliography was conducted to look for other potentially eligible studies [Fig. 1].
Fig. 1.
Flow diagram showing the process of systematic review and meta-analysis.
2.3. PICO framework for the study
Participants: Infants with atypical or complex clubfeet. Intervention: Modified Ponseti technique of casting. Control: Results of management of idiopathic clubfeet with Ponseti casting. Outcomes: Number of casts required for correction, percentage of cases requiring PAT, need for additional soft tissue procedures, complication rates during the course of casting, and relapse rates.
2.4. Inclusion and exclusion criteria
Randomized controlled trials (RCTs), cohort studies, case-control studies, and case series reporting on the outcomes after treatment of complex or atypical clubfeet with modified Ponseti technique were included. Case reports, review articles, animal studies, biomechanical studies, cadaveric studies, and conference abstracts were excluded.
2.5. Data extraction
The articles obtained from the literature search were screened based on title and abstract by two authors independently (VB and KR). Articles were excluded based on the pre-defined inclusion and exclusion criteria. Whenever there was any doubt regarding the eligibility of any article, the full text was obtained and reviewed. Any conflict regarding the inclusion or exclusion of studies among the two authors was resolved by discussion with all the authors. The data from the included studies were extracted into spreadsheets, including the name of the first author, study design, number of patients and number of feet, their mean age, rate of PAT, mean number of casts required for correction, pre-and post-treatment Pirani scores, complication and relapse rates, and period of follow-up.
2.6. Statistical analysis
Extracted data were entered into OpenMeta Analyst software for Windows 10 (cebm.brown.edu/openmeta), which is an open-source software. A pooled analysis of data was carried out, including the mean number of casts required for correction, rate of PAT, need for additional soft tissue procedures, complication and relapse rates. Heterogeneity in the included studies was reported using the I2 statistics. We chose a random-effects model since the studies were found to have high variability in reporting outcomes. 95% confidence intervals were used.
2.7. Risk of bias assessment
Methodological Index for Non-Randomized Studies (MINORS) tool (for the non-randomized studies) was used by two authors (KR and VB) to assess the risk of bias amongst the included studies. This tool consisted of 8 items that were scored for non-comparative studies.
3. Results
3.1. Study characteristics
A total of ten studies were included; all of which were case series.5,7, 8, 9, 10, 11, 12, 13, 14, 15 There were four prospective10,12, 13, 14 and six retrospective studies.5,7, 8, 9,11,15 Table 1 summarizes the different characteristics like study design, number of feet, mean number of casts required for correction, mean pre- and post-casting Pirani scores, PAT rate, complication rate during casting and relapse rates of the included studies. In total, there were 240 patients with 354 clubfeet. 65% were males, and the remaining were females. The mean age was 4.9 months (1.2–17.7 months). They had been followed up for a mean of 34 months (range 5–86.4 months).
Table 1.
Summary of the included studies showing different characteristics, mean number of casts required for correction, complication, and relapse rates.
| Author, Year | Country/Region | Study Design | No. of patients (no. of feet) | Mean Age in months (SD) | Male/Female | PAT % | Mean no. of casts required for correction (SD) | Soft tissue proce-dures | Mean pre-treatment Pirani score (SD) | Mean post-treatment Pirani score (SD) | No. of compli-cations | No. of relapse | Mean Follow-up in months (SD) | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Allende et al.∗9 2020 | Latin America | Retrospective Multicentric | 79 (124) | 7 (15) | 44/35 | 96% (119/124) | 5 (1.3) | 2/124 | 6 (1) | 0.5 (0.5) | 7/124 | 37/124 | 49 (30) |
| 2 | Bozkurt et al.10 2021 | Turkey | Prospective case series | 11 (16) | 2 (1.66) | 10/1 | 100% (16/16) | 7 (0.75) | NR | 5.2 (0.5) | 0.4 (0.4) | 7/16 | 3/11 | 13.3 (1.5) |
| 3 | Duman et al.11 2020 | Turkey | Retrospective case series | 21 (32) | 4 (2.5) | 15/8 | 93.8% (30/32) | 5 (1.3) | 6/32 | 5.1 (0.5) | NR | NR | 4/32 | 56 (30) |
| 4 | Dragoni et al.8 2018 | Italy | Retrospective case series | 9 (9) | NR | NR | 100% (9/9) | 6 (1) | 5/9 | NR | NR | NR | 5/9 | 86.4 (10.8) |
| 5 | Elseddik et al.12 2018 | Egypt | Prospective case series | 19 (28) | 1.25 (2.3) | 14/5 | 100% (28/28) | 5.6 (1) | 0/28 | 6 (0) | 0 (0.12) | 4/19 | 0/28 | 7.5 (1.4) |
| 6 | Gupta et al.13 2015 | India | Prospective case series | 16 (16) | 3.2 (1) | 10/6 | 100% (16/16) | 7 (1.25) | 0/16 | NR | NR | NR | 0/16 | 24 (6) |
| 7 | Mandlecha et al.14 2019 | India | Prospective case series | 16 (27) | 4.77 | 13/3 | 100% (27/27) | 7.44 (1) | NR | 5.6 (0.38) | 0.06 | 8/27 | 3/27 | 14.8 (4) |
| 8 | Matar et al.7 2017 | United Kingdom | Retrospective case series | 11 (17) | 1.2 (2) | 9/2 | 100% (17/17) | 7 (1.25) | 6/17 | 5.5 (0.38) | NR | NR | 9/17 | 84 (24) |
| 9 | Ponseti et al.5 2006 | USA | Retrospective case series | 50 (75) | 3 (2.2) | 31/19 | 100% (75/75) | 5 (2.25) | 2/50 | NR | NR | 11/50 | 7/50 | NR |
| 10 | Yoshioka et al.15 2010 | USA | Retrospective case series | 8 (10) | 17.7 (11.25) | 5/3 | NR | 5 (1.75) | 1/8 | NR | NR | 8/111 | 3/8 | 15.8 (5) |
NR: Not reported in original article; ∗ Allende et al. used median values instead of mean for measuring outcome parameters.
4. Primary results
4.1. The number of casts required for successful correction
Initial correction of deformity was achieved in all the feet using the modified Ponseti technique. Pooled data analysis showed that a mean of 6 (95% CI: 5.3–6.6) casts were required for the initial successful correction [Fig. 2].
Fig. 2.
A pooled analysis of the studies shows a mean number of casts required for successful correction.
4.2. Rate of PAT
PAT was carried out for all the cases in seven out of the nine studies that reported on it.5, 6, 7,10,12, 13, 14 The overall rate of PAT in complex clubfoot was estimated to be 98.3% (95% CI: 96.9–99.6). PAT was carried out before applying the final cast to correct the rigid equinus. A mean dorsiflexion of 15° was achieved after the tenotomy [Fig. 3].
Fig. 3.
A pooled analysis of the studies shows the rate of PAT.
5. Secondary results
5.1. Rate of complications during casting
The complication rates were reported in six studies.5,9,10,12,14,15 The pooled estimate of data showed that the mean complication rate was 16.8% (95% CI: 8.5–25). The various complications reported were erythema, swelling, allergic contact dermatitis, sores, rocker-bottom deformity, midfoot hyperabduction, and cast slippage [Fig. 4].
Fig. 4.
A pooled analysis of the studies shows complication rates.
5.2. Requirement for additional soft tissue procedures
Six studies reported on the need for an additional soft tissue procedure other than a PAT.5,7, 8, 9,11,15 The additional procedures performed were transfer of the tibialis anterior tendon, posteromedial soft tissue release, and plantar fascia release. Overall, the rate of additional soft tissue procedure was 7.2% (95% CI: 1.9–12.5). [Fig. 5].
Fig. 5.
A pooled analysis of the studies shows the requirement of additional soft tissue procedures.
5.3. Relapse rates
Eight studies reported on the relapse of the deformity. The overall relapse rate among all the studies was found to be 19.8% (95% CI: 10.1–29.5) [Fig. 6]. The rate of relapse was found to be higher in those studies that had followed up the patients for longer periods. The relapse rate was as high as 55.6% in the study with the longest (mean 86 months) follow-up.8 Different authors managed the relapses by different methods. These included a re-manipulation and casting, a transfer of anterior tibialis tendon in cases with dynamic swing phase supination, repeat PAT, or other soft tissue procedures.8, 9, 10, 11
Fig. 6.
A pooled analysis of the studies shows relapse rates.
5.4. Risk of bias assessment
The mean MINORS score for the included studies was 12.2 ± 1.6 (scored out of 16). Only one study had a score of 8,13 while all the other studies scored 11 or more [Table 2]. Due to the observational nature, all included studies were considered to be of very low to low-grade quality according to GRADE criteria.16
Table 2.
Quality assessment using MINORS tool for the included observational studies.
| S.No | Study | A clearly stated aim | Inclusion of consecutive patients | Prospective collection of data | Endpoints appropriate to the aim of the study | Unbiased assessment of the study endpoints | Follow-up period appropriate to the aim of the study | Loss to follow-up less than 5% | Prospective calculation of the study size | Total Score [out of 16] |
|---|---|---|---|---|---|---|---|---|---|---|
| 1. | Allende et al. | 2 | 2 | 1 | 2 | 2 | 2 | 2 | 0 | 13 |
| 2. | Bozkurt et al. | 2 | 2 | 2 | 2 | 2 | 1 | 2 | 0 | 13 |
| 3. | Duman et al. | 2 | 2 | 1 | 2 | 2 | 2 | 2 | 0 | 13 |
| 4. | Dragoni et al. | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 0 | 14 |
| 5. | Elseddik et al. | 2 | 2 | 2 | 1 | 2 | 1 | 2 | 0 | 12 |
| 6. | Gupta et al. | 2 | 2 | 1 | 0 | 0 | 1 | 2 | 0 | 8 |
| 7. | Mandlecha et al. | 2 | 2 | 2 | 1 | 2 | 1 | 2 | 0 | 12 |
| 8. | Matar et al. | 2 | 2 | 1 | 2 | 2 | 2 | 2 | 0 | 13 |
| 9. | Ponseti et al. | 2 | 2 | 1 | 2 | 2 | 2 | 2 | 0 | 13 |
| 10. | Yoshioka et al. | 2 | 2 | 1 | 2 | 1 | 1 | 2 | 0 | 11 |
6. Discussion
It is not uncommon for those involved in the treatment of children with clubfoot to see children with atypical/complex clubfeet. While the technique suggested by Ponseti works well one does encounter many difficulties during the casting process in addition to the relapses after that. The available information on this condition is primarily as case series and this meta-analysis attempts to condense the same. The mean number of casts required for correction, the rate of PAT and other soft tissue procedures, the complication seen during casting and relapse rates have been used as surrogates for indicating the results of the modified Ponseti technique.
The etiology of an atypical/complex clubfoot is poorly understood. Ponseti observed that the atypical clubfeet resulted from a significantly shortened and fibrotic Achilles tendon with contracted deep plantar intrinsic muscles and tight ligaments within the foot.5 In complex clubfoot cases, peripheral neurological dysfunctions were reported.15,17 In their series, Yoshioka et al.15 noticed that 8 out of 111 complex clubfoot patients had peroneal nerve dysfunction. The severity of dysfunction varies from weakness of active dorsiflexion of toes and ankle to no active dorsiflexion. Edmonds et al.17 mentioned the lack of active dorsiflexion of toes as a “drop-toe” sign, and it should be clinically evaluated before starting casting and during the treatment course. The complex clubfeet associated with peroneal nerve dysfunction are difficult to treat, and relapses/recurrences were expected.
Matar et al. noted that improper casting technique contributed to the development of complex deformities.7 In Ponseti's series, 6.5% of idiopathic clubfeet were atypical, and 68% of these cases were boys.5 Matar et al. found that two-third of these feet had an associated anterolateral bowing of the tibia. They also observed that in the unilateral atypical clubfeet, the size difference between the involved foot and the unaffected foot was much more significant than what was seen in idiopathic clubfeet.7 As per the current meta-analysis, a mean of six cast changes were needed for achieving a correction. While the mean number of casts is 6, there seems to be a bimodal distribution of population, with four studies having a mean of 5 and another four with a mean of 7 casts [Fig. 2]. Many surgeons treating these feet, often find that a higher number of casts are required than the usual idiopathic clubfeet. We believe that as the studies on the number of casts usually take into consideration the number of all the casts applied and not those applied specifically by the modified Ponseti method a mismatch can actually happen. These complex clubfeet must be detected at the earliest so that the casting protocol could be appropriately changed to the modified Ponseti technique. A delay in recognition could lead to a midfoot break by continuing manipulation beyond 40° of abduction. In idiopathic clubfoot also, the mean number of casts required for initial correction using the Ponseti technique is almost similar, ranging from 5 to 7 casts.18
PAT is a crucial aspect of managing complex clubfeet, as the Achilles tendon remains taut and fibrotic in these children. Some cases may require a few additional cast changes even after the tenotomy to achieve adequate ankle dorsiflexion.7 The PAT is performed 1.5 cm above the posterior skin crease of the heel, as opposed to 1 cm above in idiopathic clubfoot.5 This is expected to prevent any damage to the high riding posterior tuberosity of the calcaneus. Overall, a PAT was carried out in a mean of 98.3% cases included in this analysis. Several studies performed PAT in all cases of complex clubfeet.5,7,8,10,12, 13, 14 Bor et al.19 in their study on idiopathic clubfoot managed by Ponseti method, with a minimum five-year follow-up mentioned the rate of PAT as 86.1%. There is a high incidence of additional soft tissue procedures being carried out in these complex clubfeet, with a mean of 7.2% cases requiring the same. Transfer of tibialis anterior tendon to correct dynamic swing phase supination was the most common procedure performed. In idiopathic clubfoot, it is varied in different studies and in their series on idiopathic clubfoot, Bor et al.19 mentioned the need for additional soft tissue procedures apart from PAT as high as 32.4%.
The use of modified Ponseti technique has been associated with various complications during the course of casting such as erythema, swelling, allergic contact dermatitis, pressure sores, rocker-bottom deformity, midfoot hyperabduction, and cast slippage. The mean overall complication rate was 16.8%. Many of these complications were attributed in the articles to improper technique. Midfoot hyperabduction can be best avoided by not abducting such a foot beyond 40° during manipulation and casting. This varies from an idiopathic clubfoot where an abduction of 60°–70° needs to be achieved before a tenotomy must be recognized. Cast slippage may be avoided by keeping the knee in 110° flexion instead of 90°. Most studies do not distinguish between idiopathic atypical clubfoot and a previously treated clubfoot becoming complex due to improper techniques.7,10,12, 13, 14, 15 Nonetheless, the modified Ponseti technique effectively corrects both the idiopathic atypical clubfeet, and complex iatrogenic clubfeet.
As per the current review, the mean rate of relapse was 19.8%. However, we believe that the actual relapse rates might be even higher if the patients had been followed up for a longer duration in those studies where the follow-ups were short, as is evident from the high relapse rate of over 50% in those studies which have an extended follow-up.7,8 The relapses were treated by re-manipulation and casting, transfer of anterior tibialis tendon in cases with dynamic swing phase supination, repeat PAT, or other soft tissue procedures.8, 9, 10, 11 The reason for relapse has not been described in any of the studies. There was insufficient information regarding parental compliance to the bracing protocol after casting. Similar to an idiopathic clubfoot, non-adherence to bracing might be the key factor leading to a relapse of the deformity in atypical/complex clubfeet.20 A recent systematic review on idiopathic clubfoot mentioned that the relapse rate of these feet varied between 1.9% and 45%.21 It increases with follow-up time. A mean of 16.8% was seen in those studies with <4 years follow-up and up to 32% in ≥4 years follow-up. Another systematic review by Rastogi and Agarwal22 included the studies only with a minimum of 10 years follow-up, and they found a mean relapse rate of 47% with a mean follow-up of 14.5 years. To calculate the exact relapse rates, long-term follow-up of atypical/complex clubfeet is needed. Al-Mohrej et al. have conducted a systematic review on atypical or complex clubfeet treated using modified Ponseti casting protocol; however, while they have described the available studies in detail, a statistical analysis in the form of meta-analysis lacks in their report.23
This meta-analysis has some limitations. We could not find studies of a higher level of evidence (better than case series) comparing complex clubfoot with idiopathic clubfoot. Hence, we included case series on the topic. We believe this might be due to the uncommon nature of the condition and that proper identification of atypical/complex clubfeet is often not done. The follow-up period in some of the included studies was short, which may have led to underestimating long-term outcomes such as relapse rates. Included studies also did not distinguish between idiopathic atypical clubfoot and complex iatrogenic clubfoot, which might lead to a bias since both these groups might have some difference even though the management is similar. We believe that this review has made us wiser on the limitations of the existing studies on the topic and that a uniform terminology must be adapted for identifying and reporting them. Additionally, a universally accepted method of reporting the outcomes and complications of this uncommon yet highly plausible condition must be adopted so that robust evidence might come out of any future studies. The awareness of surgeons of the modified Ponseti method might be limited too.
7. Conclusion
The modified Ponseti technique is an effective method for managing atypical/complex clubfoot, with a high initial correction rate. Although the rate of PAT is slightly higher in the Modified Ponseti technique, the remaining parameters like mean number of casts required for initial correction, the requirement of additional soft tissue procedures apart from PAT, relapse rates are comparable with results of idiopathic clubfoot managed using the Ponseti method of casting. However, these children should be kept under follow-up for a longer duration as more relapses are expected.
Ethical standard statement
As this is a Meta-analysis of literature data, approval by Institutional Ethics committee was deemed unnecessary.
Source of funding
Nil. None of the authors received financial support for this study.
Consent to participate
Not applicable as it is a Meta-analysis and did not involve direct patient care.
Consent to publish
Not applicable as it is a Meta-analysis and did not involve direct patient care.
CRediT authorship contribution statement
Karthick Rangasamy: Concept and design of work, drafted and revised the manuscript. Vishnu Baburaj: Manuscript drafting and Meta-analysis of data. Nirmal Raj Gopinathan: Data curation, Supervision. Prateek Behera: Critical revision of manuscript. Pebam Sudesh: Data analysis and critical revision of manuscript. Sabarathinam Ravi Subramanian: Data curation, and Manuscript drafting.
Declaration of competing interest
None.
Acknowledgements
None.
Contributor Information
Karthick Rangasamy, Email: drsrk05@gmail.com.
Vishnu Baburaj, Email: drvbms@gmail.com.
Nirmal Raj Gopinathan, Email: dr.nirmalraj78@gmail.com.
Prateek Behera, Email: pbehera15@gmail.com.
Pebam Sudesh, Email: sudesh_lenica@rediffmail.com.
Sabarathinam Ravi Subramanian, Email: drsabarathinamravi@gmail.com.
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